U.S. sanctions against Venezuelan officials include a key figure in some of the oil-for-cash deals with China that are central for the survival of Petroleos de Venezuela SA.

Simon Zerpa, vice president of finance for PDVSA, is the only current official of the state-owned oil company among 13 Venezuelan nationals who were sanctioned by President Donald Trump Wednesday. A self-taught diplomat and socialist financier, he’s managing the debt of one of the most distressed borrowers in emerging markets. Zerpa, 33, also helps direct the $45 billion that Venezuela has borrowed from China to boost crude production.

The sanctions come at a time when PDVSA is struggling to make ends meet. Oil production is slumping, despite the world’s largest proved reserves. The company has an upcoming debt payment of $3.2 billion this year, most of it due in October and November. Earlier this month, Zerpa sought to improve communication with investors through invitation-only conference calls, after Goldman Sachs Group Inc. was grilled for buying Venezuelan “hunger bonds” that, according to the opposition, helped to keep president Nicolas Maduro in power.

“It’s a huge blow in terms of new financing to Venezuela,” Alejandro Grisanti, director of the Caracas-based consultancy Ecoanalitica, says by phone. “After all, Zerpa manages all the finances not just for PDVSA but also for the Venezuelan government.”

Wednesday’s sanctions include freezing the 13 individuals’ assets in U.S. jurisdiction and prohibiting U.S. citizens from dealing with them. Carlos Erik Malpica Flores, a former PDVSA treasurer and former Treasury secretary, is also part of the list.

Ambassador’s Son

Zerpa was introduced to Maduro’s inner circle through his father, Ivan Zerpa, a local politician who later became ambassador to China, according to a person familiar with his career who asked not to be named. In his mid-20s, Simon Zerpa started working for Maduro in the Foreign Ministry in the so-called “mobile office” which accompanied the president on foreign trips, and as such, worked on all deals with foreign countries, including China. He became head of the mobile cabinet when Maduro assumed the presidency after Hugo Chavez’s death in 2013.

His ties with China grew stronger over the years. Simon Zerpa was appointed commissioner for the Joint Chinese-Venezuelan fund in 2013, and he later became the country’s representative at China’s Asian Infrastructure Investment Bank.

The sanctions won’t affect U.S. oil imports from Venezuela, at least for now. White House officials are waiting for the result of the July 30 vote for representatives to the National Constituent Assembly, which will write the country’s new constitution. If the assembly of supporters to the regime helps Maduro to tighten his grip on power, the Trump administration is ready to take significant action in response, according to a senior administration official who briefed reporters on the matter.